Thursday, 24 October 2013

Summary: Aquaponic system bio-filter crash likely caused by chloramine poisoning of bacteria, which then led to buildup of high levels of ammonia. Subsequent treatments to reduce ammonia in the system ultimately proved ineffective. Follow us through our trials and tribulations as we tried to avert an aquaponist’s nightmare scenario.

Chapter 4: In Aquaponics, the Solution Finds You

Like a doctor diagnosing an elusive condition, we moved away from parsimony and conducted a more extensive investigation. There was no question that our bacteria had died since our last major water change, which occurred after we delivered our resident tilapia to a customer’s house. What was also clear was that the chloramines in the municipal water supply had killed our bacteria. But what was unclear was why the beneficial bacteria had not returned, given all other conditions were similar prior to our problem, e.g. the water being treated with dechlorinators and dechloraminators before any water changes took place? We even added bacteria into our system to speed up the cycling but the ammonia levels remained off the charts.

We decided the problem was the brand of bacteria we added. Some products can give the false illusion of a recovering system. Confirming our suspicions with some research on these products, we were concluded that the bacterial solution and the dechlorinators did not get the job done. It turned out the additive we were using contained a land based form of the bacteria which does not last. The temporary reduction of pH was most likely caused by the bacteria initially nitrifying the ammonia and then subsequently drowning.

After switching to a better brand of water conditioner and bacteria (Seachem Prime and Stability), we saw tell-tale signs of beneficial bacteria growth. First the pH dropped significantly, the Nitrosomonas had begun to metabolize the ammonia. Second, the ammonia levels dropped below 4ppm throughout the whole system, for the first time since the crash, without us changing out any water. Finally, the nitrite levels were on the rise, sign that the Nitrospiras were coming back, albeit reaching no more than 0.5ppm. This condition persisted for a couple days and we thought the problem was over. But only time would tell if we could really take a breather…